The present invention relates in general to apparatus for separating solids which are entrained within a flue gas flowing within a circulating fluidized bed (CFB) boiler. In particular, the present invention relates to a new and useful apparatus for separating solids from the flue gas using a U-beam impact type particle separator array integrated with the water and/or steam circuit of a CFB boiler enclosure.
In the CFB power plant field, the separation of solids which are entrained within the flue gas, and the recycle system for returning these solids to a bed of the CFB boiler, are critical to the efficient operation of the boiler. The separation and recycle system has a great impact on the capital and operating costs of the CFB boiler and its ability to follow variations in loads.
Presently known systems for separating the solids from the flue gas in a CFB boiler include a cyclone particle separator system (FIG. 1) and an impact type particle separator system (FIG. 2). In FIG. 1, a cyclone particle separator system 15 uses a cyclone primary separator 1, in conjunction with a furnace 8 which channels solids/gas flow 13 to the cyclone primary separator 1. Solids are collected by the cyclone primary separator 1 and recycled to the furnace 8 through a non-mechanical valve known as a loop seal 3a. The known CFB boilers having the cyclone separator system 15 also employ convection surfaces 9, air heaters 10 and secondary solids and recycle systems such as a secondary collector 4, a secondary collector purge 7, a secondary recycle line means 5, a baghouse 11, and a baghouse recycle line means 6.
In FIG. 2, an impact type particle separator system 17 uses an impact primary particle separator 1' in conjunction with a furnace 8 which channels solids/gas flow 13 to the impact type primary particle separator 1'. Solids are collected by the impact type particle separator 1', stored in a particle storage hopper 2 for collecting the solids, and recycled to the furnace 8 by means of an L-valve 3.
U.S. Pat. No. 4,992,085 to Belin et al. discloses an internal impact type particle separator employing a plurality of U-shaped impingement members organized in at least two staggered rows and positioned in the stream of a flue gas for entraining solid particles.
U.S. Pat. No. 5,025,755 to Eickvonder et al. discloses a labyrinth separator having staggered beams having essentially a U-shaped cross-section configuration. The labyrinth separator is located in a top region of the fluidized bed reactor.
U.S. Pat. No. 4,951,611 to Abdulally et al. discloses an internal solids separator system comprising a plurality of separator tubes which are water or steam cooled. The tubes have a pair of fins extending from diametrically opposed portions of the tubes for entraining solids from the gases.